Yeah,it is in Fallout: New Vegas, and the gun is called "That Gun" In fallout three there was a mission called "The Replicated Man" where a group of bounty hunters were searching for a replicant type person.

Its one of the few games I never got rid of. Tried it again on my old comp a few years back but there were bugs in it as a result of the age of the game. Might have to give it another spin on my new rig see how it works._________________